Firefox Issue

OK, this might be a little hard to understand, but I'll try and explain it as best I could. Here goes:
I use Firefox as my main browser, and for as long as I can remember, when it opens, it opens to a fairly normal-sized browser window, taking up maybe a little over half the screen size. Whenever I opened a new window, it opened a similar-sized window, slightly offset from the first. However, I must have hit some 'magic keystroke' and now every browser window I open is the FULL size of my screen. Needless to say, this is not what I want. I shrink it down to the former size, but whenever I open a new one, or even quit and reopen the program, the browser window now opens to full size. It used to be that if it did that, I could shrink it down, then open a new browser window and it would pop back to the proper size, but that is not working this time. Anyone know what I might have done and more importantly how to fix it? Thanks in advance!

This topic has come up before. Try this - set the window size to what you want, and then either close it - and then reopen a new window; or, quit FFox after resizing a window to what you want - and then reopen. That usually works.

Yeah, I tried that already- that was what I was trying to describe in the last sentence. Man, I hope I don't have to switch to Safari.

Try resetting your PRAM

Reboot but hold command option p and r wait until you hear the startup chime for a second time. Then release the keys and let the computer boot. This usually fixes odd problems like that for me

If you need more help with this topic: Resetting your Mac's PRAM and NVRAM